1. Field of the Invention
The present invention relates to a planetarium and projection apparatus for same, and more specifically relates to a planetarium providing a plurality of separate and independent projection apparatus of star field projection apparatus, planet projection apparatus and the like.
2. Description of the Related Art
Conventional planetariums having a star field projection apparatus and a plurality of mutually separate and independent supplemental projection systems for projecting the sun, moon, and planets are well known. Typically, the projectors of the star field projection apparatus are supported on three to four axes, and the projectors of the supplemental projection apparatus are supported on two axes. In planetariums of the space type, a view of space as perceived from earth can be reproduced by the combined actuation of a plurality of axes. The amount of light emitted by the light source lamps of each of the projectors can be changed to reproduce changes in the luminous intensity of stars. In conventional planetariums, high performance minicomputers and engineering workstations are used as the host computers to control the aforesaid various operations, such that said host computers integratedly control all actuation of the axes Of the various projectors, light intensity of the light source lamps and the like.
FIG. 1 shows the construction of a conventional planetarium. Within a dome 1 are provided a star field projection apparatus 2, supplemental projection apparatus 3a through 3g, and a console 4 to monitor and specify the operation of said projection apparatus. The star field projector bulb 2a of the star field projection apparatus 2 is rotatable around axes I, II, and III, whereas each of the supplemental projections apparatus 3a through 3g are rotatable around axes IV and V. A control unit 10 for controlling the aforesaid devices is installed in a room 5 adjoining the dome 1, and comprises the uninterrupted power supply 7, minicomputer 8 as the host computer, servo-controller 9 for controlling the axis of each projector, and distribution board 6. The control unit 10 and console 4 are connected via a digital signal line L11 and a power line L12 for supplying power to the console 4. The control unit 10 is connected to the star field projection apparatus 2 and supplemental projection apparatus 3a through 3g via the control lines L13 and L14 to supply power to each projector and supply feedback signals from each projector to the control unit 10, respectively.
The aforesaid control unit 10 is necessarily large in order to control the many axes and light source lamps, and a cooling unit must be provided to cool the control unit 10 due to the temperature rise produced by the heat generated by said control unit 10 itself. The cooling unit thus becomes a new source of noise. Conventionally, an air-conditioning unit has been provided in the adjoining room 5 outside the dome 1, and the control unit 10 has been installed in said adjoining room 5. When the control unit 10 is installed outside the dome 1, said control unit 10 and the objects of its control are separated by a distance, such that the cables connecting said control unit 10 and the various objects of its control must be of a length reaching 20 to 30 m. Although FIG. 1 shows only four cables L11 through L14, in actual practice in excess of 100 cables are required. Each of said cables is quite thick and nonflexible due to the necessity of providing various types of shielding for electrical noise. Thus, conventional planetariums must use a large quantity of quite long, expensive cables, which is a source of increased cost, and leads to various disadvantages in the work of installing said cables.
FIG. 2 is a block diagram showing the control circuit of a conventional planetarium. A personal computer 55 is built into the console 4. Connected to said personal computer 55 are a keyboard 51, various types of switches 52, data input means such as volume control 53 and the like, and a display unit 54 for displaying various types of information. The personal computer 55 is connected to a minicomputer 8 via the general purpose interface bus (GP-IB) 56, digital signal line L11, and GP-IB 58. A plurality of servo-controllers 61-1, 61-2, . . . , and the like and dimmer amplifiers (amps) 63-1, 63-2, . . . , and the like provided for each projector are connected to the bus line 60 of the minicomputer 8. The servo-controller 61-1 is connected via the servo-amp 62-1 to the motor 23 for driving axis I of the star field projection apparatus 2. Provided on axis I are a torque generator 25 for detecting the rotational speed of said axis I and, and an incremental encoder 26 for detecting the amount of said rotation. The servo-controller 61-1 and servo-amp 62-1 are provided within the servo-control unit 9.
When the minicomputer 8 computes the coordinate position of axis I, the servo-controller 61-1 controls the servo-amp in accordance with the result of said computation and the feedback signals from the incremental encoder 26. The servo-amp 62-1 outputs power in accordance with the specifications from the servo-controller 61-1 and the feedback signals form the incremental encoder 25 so as to actuate the motor 23. The dimmer amp 63-1 is connected to the light source lamp 24, and outputs power in accordance with the specifications from the minicomputer 8 so as to control the amount of light emitted by said light source lamp 24.
Although the control circuit in FIG. 2 is described using the light source lamp 24 and drive motor 23 of axis I as examples, it is to be noted that in the present embodiment as described above a plurality of axes and light source lamps are the objects of control, such that, in practice, servo-controllers 61 and servo-amps 62 are provided so as to correspond to the number of axes to be controlled a servo-controller 61-2 and a servo-amp 62-2 are also illustrated in FIG. 2, whereas the dimmer amps 63 are provided so as to correspond to the number of light source lamps. Three cables are used for driving the single motor 23, such that the number of cables used in the entire planetarium as described above is estimated to easily exceed 100 cables.
FIG. 3 is a flow chart showing the control of the axes via the minicomputer 8. This routine is called when specified by operators from the console, and when specified during the automated computation program. In step S1, a check is made to determine whether or not all axes have completed movement to their objective positions. When all axes have not completed movement to their objective positions, the processes of step S2 and subsequent steps are executed. In step S2 and thereafter, various parameters such as the performance date, viewer coordinates, drive speed of each axis and the like are input from the personal computer 15 of the console 4, and the date of the performance date according to the Julian calendar is computed (steps S2, S3). Then, the fixed star position is calculated based on the date computed according to the Julian calendar, the results are converted to coordinates on the dome, and the amount of rotation is computed for axes I, II, and III of the star field projection apparatus 2 necessary to project the fixed star at said coordinates (steps S4, S5, S6). In steps S7 through S11, calculations are made to determine the projection positions of the planets. Although this calculation must be executed for each of the planets, which change as sequential objects, so as to be executed seven times in accordance with the number of supplemental projection apparatus 3a through 3g, only a single calculation is shown in the drawing for the sake of simplicity. That is, the coordinates of the planets on the performance date are calculated relative to a solar ecliptic coordinate system (Step S7). Based on the aforesaid calculated coordinates, the planet viewing direction is determined from the input viewer coordinates, and the results are converted to coordinates in an equatorial coordinate system (step S8, S9). Continuing, the aforesaid results are converted to coordinates on the dome, and the amount of rotation is calculated for axes IV and V of the supplemental projection apparatus necessary to project the planet at said coordinates (steps S10, S11). Based on the aforesaid calculation results, motor drive instructions are initiated for each servo-controller 21-1, 21-2, . . . , and the like (steps S12, S13).
In a conventional planetarium as described above, the amount of rotation of all axes of the star fields projection apparatus 2 and the supplemental projection apparatus 3a through 3g are stored in minicomputer 8 and controlled by a single software routine. Although not illustrated in the drawings, the amount of light emitted by all light source lamps are similarly controlled by a single software routine. Thus, the minicomputer 8 alone is responsible for executing many processes, and must execute said many processes at high speed to accomplish a smooth performance. Accordingly, the minicomputer 8 must be a very high performance machine. When a user desires to increase the number of installed supplemental projectors, extensive labor must be expended because a large amount of software stored in the minicomputer 8 must be modified in accordance with said desires, with the result that the user's desires cannot be adequately addressed.